The present invention relates generally to ultrasonic imaging catheters, and more particularly, to catheters having improved electrical connections for ultrasonic transducers.
Intravascular imaging of blood vessels and surrounding tissues continues to be of great benefit in a wide range of medical fields. A particularly successful design for an intravascular imaging catheter employs a rotatable imaging assembly containing an ultrasonic transducer, where the assembly is attached to the distal end of a flexible drive cable. The transducer may be rotated within a catheter body or sheath in order to transmit an ultrasonic signal and produce a video image by well-known techniques. The transducer element or elements are connected to electronics, typically maintained outside the patient's body, to produce the video image.
To connect the transducer to the electronics, an electrode or lead typically is physically attached to either the transducer face, or to the face of a matching layer which is, in turn, attached to the transducer face. However, such an attachment (e.g., a soldered silver attachment point) can adversely affect the transmission and receipt of ultrasonic signals by the transducer. In short, the attachment interferes with or blocks at least part of the transmitted and/or reflected signals. This problem is further exacerbated by the fact that such attachments often are made by hand. Attachments made by hand typically vary in both size and location from catheter to catheter. As a result, it can be difficult to predict the amount of interference the attachment will produce for a particular imaging catheter.
The placement and attachment of the transducer onto the imaging assembly likewise presents difficulties. For example, it often is desirable to attach the transducer element to the imaging assembly so that the element is positioned at a certain angle, or a desired offset, with respect to the assembly centerline. For transducers that are placed and affixed by hand, the angle and offset can vary between otherwise identical catheters.